Association Between Gravidity and Anemia in Tabari Cohort Population: A Case-Control Study.

Anemia is a global public health concern. It is more prevalent in women and previous studies have mostly been limited to pregnant women. Therefore, this study aimed to investigate the association between gravidity and anemia in a subset of women enrolled in the Tabari Cohort study. This case-control study included 1676 women aged 35-70 years old with at least one pregnancy. The case group consisted of 838 women who were anemic by definition, and were included using the census method. The control group (838 women) was randomly selected from the rest of the study population based on age. In this study, a subset of data from the enrolment phase of the Tabari cohort was analyzed. Statistical analysis was performed using multivariate logistic regression, chi-square test, and independent sample t-test in SPSS. The mean gravidity in the case and control group was 3.23 ± 1.74 and 3.53 ± 1.98, respectively (P = 0.001).In the case group, the frequencies of 1, 2, 3, 4, and ≥ 5 gravidity was 10.3%, 30.2%, 25.8%, 15.5%, and 18.3%, respectively; in the control group, the frequencies were 8.2%, 27.8%, 24.7%, 14.9%, and 24.3%, respectively (P = 0.036). After adjusting for all confounding variables, the OR (95%CI) of gravidity 2, 3, 4, and ≥ 5 for anemia were 0.89 (0.60-1.33), 0.81 (0.52-1.26), 0.75 (0.45-1.24), and 0.52 (0.30-0.88), respectively. The findings of the present study showed that although the mean gravidity in the control group was significantly higher than that in the case group, women with gravidity ≥ 5 had a lower risk of developing anemia than those with only one pregnancy.